How to run bash scripts

[On3]

I know its a simple task, but when I go to run them it doesnt work. I will attach my attempts along with my bash script files to show you I'm not crazy.

root@kali:~/Downloads# ls
checksec.sh cutter ghidra vuln You_know_0xDiablos.zip
root@kali:~/Downloads# ./checksec.sh vuln
bash: ./checksec.sh: Is a directory
root@kali:~/Downloads# chmod +x checksec.sh
root@kali:~/Downloads# ./checksec.sh vuln
bash: ./checksec.sh: Is a directory
root@kali:~/Downloads# cd ./checksec.sh
root@kali:~/Downloads/checksec.sh# ls
ChangeLog checksec_automator.sh checksec.sig Dockerfile.arch extras LICENSE.txt tests
checksec checksec.pub docker-compose.yml Dockerfile.ubuntu kernel_configs README.md
root@kali:~/Downloads/checksec.sh#